A process of using inorganic acids such as sulfuric acid as a dehydration catalyst of 1,4-butandiol is disclosed in U.S. Pat. No. 4,665,205. However, by this process, the inorganic acid of catalyst is dangerous to use and causes a corrosion of equipments for reaction, thereby it being problematic.
Other catalysts for dehydration are, for example, an alumina catalyst as disclosed in U.S. Pat. No. 6,204,399; a silica-alumina catalyst as disclosed in JP-A No. H09-059191; a tungsten oxide catalyst supported on alumina as disclosed in U.S. Pat. No. 4,136,099; or a heteropoly acid catalyst as disclosed in JP-A No. S61-126080. Furthermore, it is a known method to use these acidic catalysts in the process of preparing tetrahydrofuran from 1,4-butandiol. However, these processes of dehydrating 1,4-butandiol have weak points relating to catalyst activity and stability.
Therefore, the present invention suggests a solution to problems of activity and stability of catalysts in known prior arts.
In order to solve the problems of low yield and a dangerous process of preparing tetrahydrofuran, it is an object of the present invention to provide a more safe and convenient process for preparing tetrahydrofuran.